Finding the Third Proportional to 8,640.56 and 12,684.94

Step by Step Solution

1. Step 1: Write the proportion equation
   8,640.56 : 12,684.94 = 12,684.94 : x
2. Step 2: Convert to fraction form
   8,640.56/12,684.94 = 12,684.94/x
3. Step 3: Cross multiply
   8,640.56x = 12,684.94 × 12,684.94
4. Step 4: Simplify right side
   8,640.56x = 160,907,639.38
5. Step 5: Solve for x
   x = 160,907,639.38/8,640.56
6. Step 6: Final answer
   x = 18,622.36